Static and dynamic numerical simulations of a generic UCAV configuration with and without control devices

Schütte, Andreas; Huber, Kerstin Claudie; Boelens, O.J.; Rooij, Michel van

doi:10.2514/6.2014-2132

Cited by 26 publications

(21 citation statements)

References 33 publications

(34 reference statements)

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“…Some of the papers in the NATO STO Task Group AVT-201 Special Sessions present the CFD validation results of the DLR-F19 wind tunnel models with and without control surfaces. 17,18,19,20 A problem of using CFD to fill tables is the mesh generation and the computational cost: to build an aerodynamic model using CFD, a separate high quality grid needs to be generated around aircraft for each control surface deflection. An aerodynamic model for stability and control also requires a large number of coupled computations for different values of motion frequency and amplitude for each configuration which makes time-accurate CFD simulations a very expensive approach.…”

Section: Introductionmentioning

confidence: 99%

Validation of Unsteady Aerodynamic Models of a Generic UCAV Using Overset Grids

Ghoreyshi

Jirasek

Cummings

et al. 2014

32nd AIAA Applied Aerodynamics Conference

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This work is part of the NATO STO Task Group AVT-201 Special Sessions being organized by the AIAA Applied Aerodynamics Technical Committee. Reduced-OrderModeling techniques based on response functions are presented and validated for unsteady aerodynamic prediction of a generic unmanned combat air vehicle with trailing edge flaps. The overset grid approach was used to move these control surfaces and simulate the flow fields around the vehicle in static and dynamic conditions and with different control surface deflections. Single meshes were also generated to study the effects of gaps present in the overset mesh and the sting geometry available in the experimental model. The Reynoldsaveraged Navier Stokes predictions were first validated by wind-tunnel static and dynamic case measurements. The flow topology over the configuration was then described for a range of angles of attack and control surface deflections. The response functions with respect to angle of attack and pitch rate were directly calculated from step motion simulations in CFD and a grid motion approach. An aerodynamic model was then created from these functions and used to predict the vehicle aerodynamic responses obtained from pitching oscillations at different amplitudes and frequencies. The results show that predictions from a linear model are only in good agreement with time-accurate simulations of small amplitude motions. A model that has response dependence on the angle of attack match quite well with CFD data of large amplitude motions within the range of data used for model generation, however, small discrepancies can also be seen in pitch moment plots. The results show that model predictions get worsen with including sting geometry in simulations because of the nonlinear hysteretic behavior of a wake formed behind the sting. Nomenclatureroll moment coefficient in wind axes Downloaded by CORNELL UNIVERSITY on July 30, 2015 | http://arc.aiaa.org |

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Section: Introductionmentioning

confidence: 99%

Validation of Unsteady Aerodynamic Models of a Generic UCAV Using Overset Grids

Ghoreyshi

Jirasek

Cummings

et al. 2014

32nd AIAA Applied Aerodynamics Conference

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“…published by Frink [42], Hitzel and Zimper [43], Kennett et al [44], Lofthouse et al [45] and Jirasek et al [46]. The TAU results are summarized by the author in Schütte et al [47].…”

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confidence: 98%

“…The flow physics of highly swept wings is dominated by a vortical flowfield, which occurs already at low angles of attack due to the separation of the flow at the leading edge. Figure 1 shows an example of the complex vortical flowfield of a generic blended-wing/body configuration with a sweep angle of 53 deg [1].…”

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confidence: 99%

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Numerical Investigations of Vortical Flow on Swept Wings with Round Leading Edges

Schütte

2017

Journal of Aircraft

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The present work is investigating the vortex-dominated flow physics as well as the aerodynamic behavior of swept wing configurations with round leading edges. The research is based on numerical simulations using the computational fluid dynamics method DLR TAU. The target configurations are swept wings of constant aspect ratio, variable leading-edge contours, and leading-edge sweep angles. The work deals with the onset of the vortical flow at the leading edge for constant and variable leading-edge nose radii, the influence of the angle of attack, the leading-edge sweep, and the onflow Mach number. Furthermore, the aerodynamic behavior is analyzed and assessed, as well as the specific flow physics in the vicinity of the vortical flow separation at round leading edges. The objective of the present work is to provide a contribution for the design and assessment of the physical characteristics of swept wing configurations. Furthermore, sensitivities will be given for the design process. In addition, the current investigation provides a deeper understanding of the separation onset process and the flow physics of swept wing configurations with round leading edges. Nomenclaturewing reference length, depth of the wing, m M ∞ = onflow Mach number, equal to a∕U ∞ p = pressure, N∕m 2 q ∞ = onflow dynamic pressure, N∕m 2 Re ∞ = Reynolds number, equal to U ∞ · c ref ∕ν r = radius at nose of the profile, m r N = nondimensional leading-edge contour radius, equal to r∕c ref s = wing semispan, m T = temperature, K t = time, s U ∞ = onflow velocity, m∕s u = local velocity within the flowfield, m∕s x, y, z = Cartesian coordinates, m y W = initial wall distance, distance of first grid point from wing surface, m y = nondimensional value to assess resolution of boundary-layer wall unit, equal to τ W ∕ρ p · y W ∕ν α = angle of attack, deg β = angle of sideslip, deg γ = circulation Δt = discrete time step, s Δx = discrete step in space, m μ = dynamic viscosity, Ns∕m 2 ν = kinematic viscosity, m 2 ∕s ρ = density, kg∕m 3 τ W = wall friction, N∕m 2 φ = wing sweep, deg k∂ρ∕∂tk = density residual, kg∕m 3 s Subscripts le = leading edge r = root ref = reference parameter ∞ = onflow condition

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“…The drag curve of the calculation result differs significantly from the experimental results. That is because of the influence coming from the sting of the wind-tunnel model, which has been analyzed in Schütte et al (2014). The aerodynamic parameters obtained by solving Navier-Stokes equation could be closer to the wind tunnel data than the presented method, but the improvements cannot have a significant impact on the flying quality of aircraft.…”

Section: Research Objectmentioning

confidence: 97%

Effect of Aerodynamic Configuration Parameters on Lateral-Directional Stability of Double-Swept Flying Wing Aircraft

Pan

Huang

2019

J.Aerosp. Technol. Manag.

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Poor lateral-directional stability due to the absence of vertical stabilizer is a great risk to the aircraft with flying wing layout. In this paper, an unmanned aerial vehicle with this kind of configuration is chosen as the research object. A threedimensional model of the unmanned aerial vehicle is established, and then the sensitivity analysis is performed to obtain the effects of main aerodynamic shape parameters on lateral-directional flying quality. The results show that the roll mode and spiral mode of the aircraft meet the requirements of Level 1 flying quality in MIL-F-8785C. But the Dutch roll mode is generally divergent, which means that the flying quality of the aircraft is unacceptable. Thus it can be seen that the Dutch roll mode is the key to the dynamic stability of the aircraft. Further studies show that increasing the value of wing aspect ratio or decreasing the values of dihedral angle and torsion angle are useful for improving the Dutch roll mode. It is valuable to reveal the influence mechanism of aerodynamic shape parameters on lateral-directional flying quality for the design of flying wing aircraft.

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Static and dynamic numerical simulations of a generic UCAV configuration with and without control devices

Cited by 26 publications

References 33 publications

Validation of Unsteady Aerodynamic Models of a Generic UCAV Using Overset Grids

Validation of Unsteady Aerodynamic Models of a Generic UCAV Using Overset Grids

Numerical Investigations of Vortical Flow on Swept Wings with Round Leading Edges

Effect of Aerodynamic Configuration Parameters on Lateral-Directional Stability of Double-Swept Flying Wing Aircraft

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